This invention relates to limpet mines. In particular, this invention relates to limpet mines that are enabled and then, armed and fired using magneto-inductive signals propagated at extremely low to very low frequencies for safe and reliable communications to the limpet mines.
Limpets are mines that can be attached to the hulls of various enemy combatants by suction cup, adhesive or magnetic means. Limpets usually are emplaced by remotely operated vehicles or swimmers. Consequently, each limpet requires fuzing that is safe and reliable yet meets certain operational requirements.
Previously, acoustic command signals have been used to control attached limpets. However, acoustic command signals have limited applications since sound cannot effectively be communicated through the air to receivers in the water. In addition, reliable communication with acoustic devices is affected by sediment, microorganism, algae, changes in salinity, thermo-clines, and multi paths in the water. Acoustic devices may also be unreliable at detecting acoustic command signals in the presence of ambient noise in the water that may come from ships, mammals, munitions, landing craft, sonar, and crashing surf. Acoustic devices are known to be incapable of reliable performance in the littoral regions associated with amphibious assault, particularly in the surf zone and noisy harbors.
A further limitation in the use of acoustic signals is that they are undesirable from a stealth perspective. If an acoustically responsive limpet is attached to the bottom of an enemy vessel and an attempt is made to arm and fire it using sonar from a friendly submarine, for example, the submarine's position would be given away and triangulated upon by other enemy combatants in the area using passive acoustic detection.
Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for a limpet that can be safely and reliably controlled by magneto-inductive signals from a remote transmitter to arm and fire the limpet on command and can be initiated with coded signals.